This remote access connect plugin for thin-edge is able to establish a WebSocket connection between c8y and a server running on the thin-edge device in addition to the usual TCP capabilities.

This functionality can be used together with the cumulocity-webrtc-webcam-plugin to view a video stream from a camera connected to the thin-edge device.

The video stream is transferred via a separate peer-to-peer connection between the users browser and a server running locally on the device using WebRTC.

For the WebRTC functionality on the thin-edge side we can utilize an existing WebRTC solution: go2rtc to stream e.g. a video feed from an USB Webcams, a Raspberry Pi camera module or any kind RTSP stream.

The remote access connect plugin is configured to establish a WebSocket connection for any operation that should connect to port 1984 on host 127.0.0.1. For all other operations it will establish the usual TCP connections that are required for e.g. SSH.

Below installation instructions have been verified on a Raspberry Pi 4 using Ubuntu 22.04 64 bit.

• uninstall the c8y-remote-access-plugin if installed:

sudo apt remove c8y-remote-access-plugin

• install a recent version of nodejs:

sudo apt update
sudo apt install curl
curl -fsSL https://deb.nodesource.com/setup_16.x | sudo -E bash -
sudo apt update
sudo apt install nodejs

• checkout this repo
• build and install the remote access connect plugin:

npm i
npm run pack
sudo npm i -g ./c8y-remote-access-*.tgz

• create the file: /etc/tedge/operations/c8y/c8y_RemoteAccessConnect with this content:

[exec]
command = "/usr/bin/c8y-remote-access"
topic = "c8y/s/ds"
on_message = "530"

• reconnect tedge:

sudo tedge disconnect c8y
sudo tedge connect c8y

• download the latest release of go2rtc that matches the architecture of your device to your current users home directory

wget https://github.com/AlexxIT/go2rtc/releases/download/v1.3.1/go2rtc_linux_arm64

• copy the go2rtc.yaml file also into your home directory
• Adjust the streams section of the go2rtc.yaml file according to your needs, just keep the tedge_cam as the name of your stream.
• You can verify the setup, by starting it temporarily by executing the previously downloaded binary:

./go2rtc_linux_arm64

by connecting to http:https://<local-ip-of-tedge>:1984/stream.html?src=tedge_cam&mode=webrtc with your browser you should be able to see the camera stream.

• Depending on your firewall setup you may also need to add a TURN server to the ice_servers section.
• You might want to adjust the listen attributes of the api, rtsp, and srtp sections of these files to be prefixed with 127.0.0.1 (e.g. 127.0.0.1:1984 for the api) to only allow local connections
• copy and adjust the go2rtc.service file to /etc/systemd/system/go2rtc.service, adjust it to your setup (e.g. the ExecStart, WorkingDirectory, User and Group settings might need to be adjusted if you are not using a user called ubuntu)
• you can then start and enable the service:

sudo systemctl start go2rtc
sudo systemctl enable go2rtc

• install the cumulocity-webrtc-webcam-plugin to cockpit and/or devicemanagement application
• create a new remote access configuration of type PASSTHROUGH and set the host to 127.0.0.1 and the port to 1984 and ensure that the name contains webcam.
• after refreshing the page or navigating another time to the device you should see a Webcam tab, where you can start the video stream

• the WebRTC connection can be e.g. debugged from firefox by visiting about:webrtc.